For some reason, tank companions just kinda suck. At about Quesh and definitely afterwards, I started having alot of trouble even with Forex or Aric out against silvers and above. Although I'm primarily a healer. My best way to use Tanno is to use him as a tank and just heal him constantly. Thats the only way I survive against golds and silvers. And it seems like if I have more than one silver, I'm screwed. I think companion tanks need fixed to make them more viable.